Can someone explain how to get the answer?

What is the value of x? enter your answer in the box.

Identify all the cases where non-probability sampling is used when attempting to study the characteristics of a large city. studies on every subject in the population divide a population in groups and obtain a sample studies with a limited amount of time demonstrate existing traits in a population studies with the nth person selected

Find the amount of simple interest earned for depositing the given principle in an account if $2200 is invested at 5.5 % for 6 months